I have had SP before. It is more likely to happen if you sleep on your back. There are 2 books written about SP, The Terror That Comes in the Night, and Wrestling With Ghosts. Wrestling With Ghosts gives a good explanation on what SP is and how to transform the experience into a lucid dream or OBE. The key thing is learning how to over come your fear of SP. I have had some neat trips myself. Happy Trails ~ Shoe